In modern medical practice, it is often desirable to block or otherwise prevent flow through the lumen of a blood vessel or other anatomical conduit. Examples of medical procedures wherein it is desirable to block the lumens of blood vessels include: a) procedures intended to diminish or block the flow of blood into vascular aneurysms (e.g., cerebral aneurysms); b) procedures intended to occlude the side branches which emanate from a segment of a peripheral vein to prepare the vein segment for use as an in situ bypass conduit; c) procedures intended to treat varicose veins; d) transvascular, catheter-based procedures for bypassing obstructed, diseased or injured arteries as described in U.S. patent application Ser. Nos. 08/730,327 and 08/730,496; e) procedures intended to block or diminish blood flow to a tumor; f) procedures intended to close congenital or acquired arterio-venous malformations; and g) procedures intended to temporarily or permanently block blood flow through a vessel as an adjuvant to placement of an endovascular graft for treatment of an aneurysm or other therapeutic intervention.
Examples of embolization devices useable to block the lumens of some blood vessels have been described in the following U.S. Pat. No. 5,382,260 to Dormandy, Jr. et al; U.S. Pat. No. 5,342,394 to Matsuno et al.; U.S. Pat. No. 5,108,407 to Geremia et al.; and U.S. Pat. No. 4,994,069 to Ritchart et al.; U.S. Pat. No. 5,382,261 to Palmaz; U.S. Pat. No. 5,486,193 to Bourne et al.; U.S. Pat. No. 5,499,995 to Teirstein; U.S. Pat. No. 5,578,074 to Mirigian; and also in Patent Cooperation Treaty International Publication No. WO96/00034 to Palermo.
The new transvascular catheter-based bypass procedures described in co-pending application Ser. Nos. 08/730,327 and 08/730,496 include certain coronary artery bypass procedures wherein a tissue-penetrating catheter is advanced, transluminally, into the coronary vasculature and is utilized to form at least one blood flow passageway (e.g., a puncture tract or interstitial tunnel) between an obstructed coronary artery and an adjacent coronary vein, at a site upstream of the arterial obstruction. Arterial blood will then flow from the obstructed coronary artery into the adjacent coronary vein. The lumen of the coronary vein is blocked or closed off immediately proximal to the first blood flow passageway such that arterial blood which enters the vein will be forced to flow through the vein in the retrograde direction. In this manner, the arterial blood from the obstructed artery may retroprofuse the myocardium through the coronary vein. Or, optionally, one or more secondary blood flow passageways (e.g., puncture tracts or interstitial tunnels) may be formed between the coronary vein into which the arterial blood has been shunted, and the obstructed artery or another coronary artery, to allow the arterial blood to re-enter the coronary arterial tree after having bypassed the arterial obstruction. In cases wherein such secondary blood flow passageways are formed between the coronary vein and one or more adjacent arteries, the lumen of the coronary vein may be blocked or closed off distal to such secondary passageways, to facilitate the re-entry of the shunted arterial blood into the coronary arterial circulation. These transvascular, catheter-based coronary artery bypass procedures present unique and heretofore unaddressed problems relating to the type(s) of blocking apparatus which may be utilized to block the lumen of the coronary vein proximal and/or distal to the arterial-venous blood flow passageways (e.g., puncture tracts or interstitial tunnels) formed during the procedure. In particular, when arterial blood is bypassed through a proximal segment of the Great Cardiac Vein, it will typically be desirable to block the lumen of the Great Cardiac Vein at or near its confluence from the coronary venous sinus. This proximal segment of the Great Cardiac Vein is of tapered or angular configuration and, as a result, the deployment of typical embolization coils of the type traditionally utilized to embolize or block the lumens of blood vessels or the defined spaces of aneurysm may be inappropriate, due to the fact that such embolization coils may become dislodged or work loose due to the gradually tapered or widening anatomy of the proximal segment of the Great Cardiac Vein.
Accordingly, there exists a need in the art for the development of new methods and apparatus for blocking or otherwise sealing the lumens of blood vessels or other anatomical conduits, and which are usable in tapered (i.e., widening) segments of blood vessel (e.g., the proximal end of the great cardiac vein) and/or are capable of being removed following implantation and/or may be punctured or traversed following implantation.